Jack Ziebell will spend the night in hospital after suffering bruising to his lungs in North Melbourne's brave eight-point loss to Port Adelaide at Etihad Stadium on Saturday night.

North communications manager Heath O'Loughlin tweeted after Saturday night's game that: "Jack Ziebell will spend night in hospital for observation. Scans will be viewed by the @NMFCOfficial medical and more info released."

North confirmed after the match that Ziebell had bruising to his lungs but said the extent of his injuries were not yet clear.

Ziebell copped a heavy knock to the abdomen as he tried to spoil Ollie Wines in a marking contest midway through the first quarter.

The Kangaroos midfielder was coughing up blood as he was helped from the field and played no further part in the game.

It was a significant blow for the Roos, who had already lost star midfielder Daniel Wells (Achilles tendon soreness) as a late withdrawal before the game.

Brad Scott said Wells had almost been fit enough to play against the Power but was still no guarantee to play against Geelong next Sunday.

"I think he'll be close (to playing against Geelong), he was really close to playing tonight," Scott said.

"We, I, made the decision that he was not 100 per cent and we need him at his best.

"If he's not quite at his best we're better off getting him right and waiting another week so that'll be the same case this week."

PRESS PLAY above to view the incident | YouTube

Sam Wright was involved in a heavy head-on collision with Port key defender Alipate Carlile soon after Ziebell left the field.

The Kangaroos defender headed into North's rooms to be assessed under the concussion sub rule, but returned to the field in the second quarter.

"He appears to be OK," Scott said.

"We used the concussion sub because the vision showed that he did get hit in the head so that happened right on the Ziebell incident as well.

"Fortunately, he came good and played out the game and played well."

North also went into Saturday night's game without Nick Dal Santo, who had hamstring surgery this week that will likely keep him out for 10-12 weeks.